From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Ian Rogers <irogers@google.com>,
Kan Liang <kan.liang@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-perf-users@vger.kernel.org, Song Liu <song@kernel.org>,
bpf@vger.kernel.org
Subject: [PATCH 5/5] perf record offcpu: Constify control data for BPF
Date: Mon, 2 Sep 2024 13:05:15 -0700 [thread overview]
Message-ID: <20240902200515.2103769-6-namhyung@kernel.org> (raw)
In-Reply-To: <20240902200515.2103769-1-namhyung@kernel.org>
The control knobs set before loading BPF programs should be declared as
'const volatile' so that it can be optimized by the BPF core.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_off_cpu.c | 16 ++++++++--------
tools/perf/util/bpf_skel/off_cpu.bpf.c | 9 +++++----
2 files changed, 13 insertions(+), 12 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 6af36142dc5a7fd0..a590a8ac1f9d42f0 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -73,14 +73,12 @@ static void off_cpu_start(void *arg)
struct evlist *evlist = arg;
/* update task filter for the given workload */
- if (!skel->bss->has_cpu && !skel->bss->has_task &&
+ if (skel->rodata->has_task && skel->rodata->uses_tgid &&
perf_thread_map__pid(evlist->core.threads, 0) != -1) {
int fd;
u32 pid;
u8 val = 1;
- skel->bss->has_task = 1;
- skel->bss->uses_tgid = 1;
fd = bpf_map__fd(skel->maps.task_filter);
pid = perf_thread_map__pid(evlist->core.threads, 0);
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
@@ -148,6 +146,7 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
if (target->cpu_list) {
ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);
bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
+ skel->rodata->has_cpu = 1;
}
if (target->pid) {
@@ -173,11 +172,16 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
ntasks = MAX_PROC;
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+ skel->rodata->has_task = 1;
+ skel->rodata->uses_tgid = 1;
} else if (target__has_task(target)) {
ntasks = perf_thread_map__nr(evlist->core.threads);
bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+ skel->rodata->has_task = 1;
} else if (target__none(target)) {
bpf_map__set_max_entries(skel->maps.task_filter, MAX_PROC);
+ skel->rodata->has_task = 1;
+ skel->rodata->uses_tgid = 1;
}
if (evlist__first(evlist)->cgrp) {
@@ -186,6 +190,7 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
if (!cgroup_is_v2("perf_event"))
skel->rodata->uses_cgroup_v1 = true;
+ skel->rodata->has_cgroup = 1;
}
if (opts->record_cgroup) {
@@ -208,7 +213,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
u32 cpu;
u8 val = 1;
- skel->bss->has_cpu = 1;
fd = bpf_map__fd(skel->maps.cpu_filter);
for (i = 0; i < ncpus; i++) {
@@ -220,8 +224,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
if (target->pid) {
u8 val = 1;
- skel->bss->has_task = 1;
- skel->bss->uses_tgid = 1;
fd = bpf_map__fd(skel->maps.task_filter);
strlist__for_each_entry(pos, pid_slist) {
@@ -240,7 +242,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
u32 pid;
u8 val = 1;
- skel->bss->has_task = 1;
fd = bpf_map__fd(skel->maps.task_filter);
for (i = 0; i < ntasks; i++) {
@@ -253,7 +254,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
struct evsel *evsel;
u8 val = 1;
- skel->bss->has_cgroup = 1;
fd = bpf_map__fd(skel->maps.cgroup_filter);
evlist__for_each_entry(evlist, evsel) {
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index d877a0a9731f9f2f..c152116df72f9bc1 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -85,10 +85,11 @@ struct task_struct___old {
} __attribute__((preserve_access_index));
int enabled = 0;
-int has_cpu = 0;
-int has_task = 0;
-int has_cgroup = 0;
-int uses_tgid = 0;
+
+const volatile int has_cpu = 0;
+const volatile int has_task = 0;
+const volatile int has_cgroup = 0;
+const volatile int uses_tgid = 0;
const volatile bool has_prev_state = false;
const volatile bool needs_cgroup = false;
--
2.46.0.469.g59c65b2a67-goog
next prev parent reply other threads:[~2024-09-02 20:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-02 20:05 [PATCHSET 0/5] perf tools: Constify BPF control data properly (v1) Namhyung Kim
2024-09-02 20:05 ` [PATCH 1/5] perf stat: Constify control data for BPF Namhyung Kim
2024-09-02 20:05 ` [PATCH 2/5] perf ftrace latency: " Namhyung Kim
2024-09-02 20:05 ` [PATCH 3/5] perf kwork: " Namhyung Kim
2024-09-02 20:05 ` [PATCH 4/5] perf lock contention: " Namhyung Kim
2024-09-02 20:05 ` Namhyung Kim [this message]
2024-09-03 15:18 ` [PATCHSET 0/5] perf tools: Constify BPF control data properly (v1) Arnaldo Carvalho de Melo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240902200515.2103769-6-namhyung@kernel.org \
--to=namhyung@kernel.org \
--cc=acme@kernel.org \
--cc=adrian.hunter@intel.com \
--cc=bpf@vger.kernel.org \
--cc=irogers@google.com \
--cc=jolsa@kernel.org \
--cc=kan.liang@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=song@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).